This is a non-contact diagnostic method that automatically detects refractive errors in the eye. Refraction of the eye is the refractive power of the eye. It depends on the radius of curvature of each of the refracting media of the eye and the distance between them. The main refractive media are the cornea, lens, vitreous body. Autorefratokeratometry assesses not only the overall refraction of the eye but also makes it possible to measure separately the refraction of the cornea. When performing autorefratokeratometry, even minor refractive errors can be detected, presented by myopia (a person sees well close objects and poorly distant ones), farsightedness (objects far away are visible well, but close ones are not), astigmatism (a distorted image of objects).
- An autorefractokeratometer emits an infrared beam that passes through the pupil and is reflected off the retina. Sensors of a special electronic unit register beam images before and after reflection, that is, at the entrance to the eye and at the exit from it. The computer program then analyzes the parameters and provides refraction values.
- An additional autorefractokeratometer unit separately determines the refraction of the cornea. To do this, he projects two horizontal and two vertical points onto the surface of the cornea, which are reflected and returned back. This is how the radius of curvature of the cornea is measured in millimeters, and then the indicator is converted to diopters.
Indications for performing autorefractokeratometry
- Assessment of visual acuity.
- Preparation for laser vision correction or other eye surgeries.
- Evaluation of the results of surgical treatment or laser correction.
Autorefratokeratometry – execution method
The patient sits down in front of the autorefractokeratometer and fixes his gaze on the image (a balloon or a Christmas tree, which are located as if in the distance). An image, and not just a dot mark, is used so that the patient can keep his gaze at one point for a long time, but at the same time, he does not strain his eyes but is in a relaxed state. This innovation has particularly increased the effectiveness of eye examinations in children. Blinking is allowed during the exploration.
Maximum relaxation of accommodation allows you to correctly determine the refraction. Autorefraktokeratometry allows you to obtain accurate indicators of anisometropia – a value that shows the difference in refraction between the right and left eyes, as well as to reliably determine the degree of astigmatism.
The study can be carried out by nursing staff since it is fully automated and does not require special knowledge, the result of the study is provided in the form of a printout, which is then deciphered by the doctor.
Autorefratokeratometry cannot be performed in patients with opaque optical media – with clouding of the lens (cataract), vitreous body, or cornea, since in this case the passage of the light beam to the retina and its reflection is disturbed.
Interpretation of results
The conclusion of autorefratokeratometry is a printout with abbreviated symbols in English and the numerical values of the shown indicants.
